BWAHAHAHAH!

A Certain Scientific Railgun gets a makeover starring a certain popular plumber.

Take the anime's opening, strip it of cute girls and replace it with Mario, Luigi and friends, and overhaul the music to be 8-bit and you'll have something like this featured video. Scene for scene, the creator of this mash-up nails it. On it's own, it's already quite funny, but when you watch the side-by-side, you'll really laugh. 

See both videos after the jump.